GASES MAY REVEAL PLANET FORMATION

By JOHN NOBLE WILFORD

Published: May 18, 1991

New and more detailed observations of gas clouds circling a star have revealed for the first time the broad structure and dynamics of what could be a planetary system in the making, or one that failed, astronomers of the Hubble Space Telescope reported yesterday.

Other astronomers said the discovery could help answer the question of whether there are planets orbiting stars other than the Sun and thus whether there could be life elsewhere in the universe.

The star is Beta Pictoris, the second-brightest in the constellation Pictor, visible from the Southern Hemisphere.

Dr. Al Boggess, an astronomer at the Goddard Space Flight Center, said the Hubble telescope had observed that a gas disk ringing the star appeared to include large clumps of matter spiraling in toward Beta Pictoris at speeds of up to 120 miles a second. The disk seemed to be part of a more rarefied gas cloud, or halo, diffusing outward into interstellar space. Ultraviolet Readings

The observations were made by the high-resolution spectrograph, an instrument sensitive to ultraviolet radiation that has been relatively unaffected by the focusing flaws in the Hubble's primary mirror.

At a news briefing at the Space Telescope Science Institute in Baltimore, Dr. Boggess said the observation was a "new phenomenon, not seen around any other star." But he said it was too early to draw any conclusions about its significance in understanding the evolution of planetary systems.

Dr. Stephen Maran, another Goddard astronomer working with the Hubble investigators, said in a telephone interview: "There is definite evidence of clumps of gas. Are these clumps leading to planets? We don't know. We don't even know what processes are forming these clumps. But it's a dynamic phenomenon that can't go on forever, because there's definite evidence of the clumps of gas falling into the star."

Dr. Maran said it was not clear whether some of the circumstellar material could eventually coalesce into planets. It was even possible, he said, that this was a remnant of a planetary system that failed.

For almost a decade astronomers have speculated that Beta Pictoris may be surrounded by a planetary system in formation. In 1983, the Infrared Astronomical Satellite detected large amounts of infrared heat coming from what appeared to be an even larger disk of dust particles around the star. Subsequent observations confirmed these findings and also detected a cloud of gas around the star.

The larger disk of dust particles is estimated to extend out several billion miles. The gas cloud is much smaller, confined to the region nearest the star.

In measurements taken 23 days apart, the spectrograph found clear evidence for turbulent movement in the gas cloud and changes in the structure of clumps in the inner disk. That disk seemed to consist of three major components: a diffuse disk circling the star in a stable manner; a smaller disk of gas that is drifting toward the star, and isolated gas clumps that are spiraling toward Beta Pictoris. Clouds Between Galaxies

In another discovery reported yesterday, astronomers said they were surprised that the Hubble's spectrograph has detected intergalactic clouds of hydrogen in regions relatively near the Milky Way. It had been widely assumed that this phenomenon was probably confined to the most distant realms of the universe.

Dr. Maran said the discovery was creating considerable excitement, even though its cosmological implications are not yet understood. They are not sure if the observed hydrogen clouds are halos around undetected galaxies, or isolated structures that failed to evolve into galaxies, or else the remnants from immense explosions accompanying galaxy formation.

The scientists reporting the hydrogen-cloud discovery were Dr. Simon L. Morris and Dr. Ray Weymann of the Observatories of the Carnegie Institution in Pasadena, Calif.; Dr. Blair Savage of the University of Wisconsin at Madison, and Dr. Ronald Gilliland of the Space Telescope Science Institute.